Determination of bezafibrate, ciprofibrate and fenofibric acid in human plasma by high-performance liquid chromatography

A selective high-performance liquid chromatographic method to assess either bezafibrate, ciprofibrate or fenofibric acid plasma levels is described. Drugs are extracted with diethyl ether, after acidification with HCl. An isocratic acetonitrile-0.02 M H3PO4 (55:45) mobile phase, a C-18 (5 mu m) column and UV detection are used. The LOQ found was 0.25 mu g/ml for the three fibrates. Intra- and inter-assay accuracy ranges were 90-107% and 82-111%; 96-115% and 94-107%; 94-114% and 94-126% for bezafibrate, ciprofibrate and fenofibric acid, respectively. Intra- and inter-assay precision (C.V.% ranges) were 1.72-3.06% and 2.66-7.67%; 1.88-4.64% and 0.62-2.99%; 1.26-4.69% and 3.56-7.17% for the three fibrates studied. Its sensitivity, accuracy and precision make it a useful tool for monitoring plasma levels of these drugs in a clinical setting and for research purposes.